Process of manufacturing artificial lustrous threads, bands, and filaments.



. TED s'rATEs PATENZFUEEIGE.

FRIEDRICH DIETLER, OF KELSTERBAOH-ON-THE MAIN, GERMANY, ASSIGNOR TO VER- EINIGTE KUNSTSEIDEFABRIKEN A. G., OF KELSTERBACH-ON-THEMAIN," GER- MANY, A CORPORATION OF GERMANY.

PROCESS OF MANUFACTURING ARTIFICIAL LUSTROUS THREADS, BANDS, AND

Patented Sept. 23, 1913.

Application filed February 14, 1912. Serial No. 677,484.

To all whom it may concern Be it known that I, FRIEDRICH Drnrnnn, a subject of the German Emperor, residing at Kelsterbach-on-the-Main, German Empire, have invented certain new and useful Improvements in Processes of Manufactur- .nate solution e. a water soluble derivative of cellulose which is obtained by treating cellulose, at low temperature, simultaneously or successively with aqueous alkali lye and carbon disulfid. For the preparation of such precipitation baths mineral acids, either alone or in combination .with salts, have been employed exclusively. Organic acids have not been heretofore used for this purpose, as the opinion was generally held that they do not act on the xantho- V i gen, but act only on the inorganic impurities. This'view has been well explained in the monograph regarding viscous substances, by Margosches, page 28, last paragraph, and page 74, paragraph 5, as well as in German Patent #133144, Class 8i.

The object of the invention disclosed by the patent just mentioned is to cleanse the raw viscose, and the patentee uses for this purpose weak organic acids in excess, such for example as acetic acid, lactic acid or formic acid, and it is maintained that the salts of the cellulosexanthogenic acids are not decomposed by these acids. I have discovered however that this contention is not warranted, in so far as formic acid is concerned. Formic acid, even of moderate concentration, rapidly converts theviscose into cellulose-hydrate. It may therefore be used directly, either alone or in combination with salt solutions, as a precipitating medium for viscose for the preparation of artificial silk, bands, filaments, etc. Its action on the viscose proceeds relatively slowly, but sufiiciently strongly to produce a thread which may be wound with great rapidity, which thread contains very littlefree sulfur, (because the decomposition of the sulfur-containing by-products is not sudden, but gradual) having a characteristic luster on the spinning bobbin, and the subsequent treatment of which is very simple. The spool or spinning bobbin is allowed to stand for a time (according to the strength of the bath employed, about 1 to 2 hours) at ordinary temperature. The thread is insoluble in water and may then. be washed, twisted, reeled or bleached.

A suitable spinning bath may be obtained in the followmg manner:--A solution of any salt, for example, ordinary table salt, saturated in the cold, is admixed with formic acid (the concentrated product found on the market) in such manner that the bath contains about 200 gr. of formic acid to the liter. The acid content is proportioned to the alkali content of the viscose used, and to the rapidity with which the threads are to be drawn through the bath. The formic acid thus not only acts on the impurities of the viscose, but also on the cellulosexanthogenate itself. This action is not a sudden one as with the strong mineral acids, but is a step-by-step action which gradually increases. As a consequence the thread is taken out in a form which requires a minimum of subsequent treatment,

In my invention, the viscous material or viscose is introduced into the precipitation bath in the form of a viscose solution as distinguished from a solution in cupro-ammoniacal liquor.

Having now described my invention, what I claim as new and desire to secure by Let 2. The herein described method of mann- In testimony whereof I have efixed my fmgugilng artifipial, lustrous thlllrealds, bands signature in presence of two witnesses. an aments rom viscose w ic consists in forming viscosesolutioninto thread like FRIEDRICH DIETLER' 5 bodies and thereafter subjecting the same Witnesses:

to the action of a precipitation bath con- 0. A. BEOHTLE, sisting of formic acid and a salt. EMIL BAUR. 

